Out of curiousity, do you, or anyone else for that matter, know if there is an easy way for the IRS to fact check that 75% or is it simply your word?
From the literature I have read, it seems American carriers supply their crews with a form that tells them how much time they have spent over foreign countries (based on flight planning), but obviously Cathay has no interest in tracking that. I suppose the IRS could ask to see your logbook, sample flight plans, etc., but I haven't known anyone here who has been audited so I can't tell you if they actually do that. I keep a spreadsheet with total DUTY time and duty time in/over foreign countries so at least there's some data they can reference if they ever decide to take a look.